The present invention relates to a heat exchanger, in particular, a refrigerant condenser, and more particularly to such a heat exchanger for motor vehicle air-conditioning units. The heat exchanger includes a block of tubes and fins and collecting tubes which are arranged on both sides and receive the ends of the tubes of the block of tubes. It also includes a collector which is arranged parallel to one of the collecting tubes and is in refrigerant communication with the collecting tube via two overflow openings.
Such collectors can be formed from a first tube, for example, a welded tube, and a second tube piece, for example, a shorter one, which comprises the two overflow openings. Such a condenser is disclosed in commonly assigned DE-A 198 48 744. The collector can also be made in one piece from one tube, in which case the tube can be formed from one part or at least two axial tube shells.
The condenser known from DE 1 98 48 744 is distinguished, inter alia, by the fact that the collector is designed in two parts. It consists, on the one hand, of a welded tube which in terms of its dimensioning, particularly its wall thickness, is adapted to the prevailing operating pressure, and, on the other hand, of a short tube piece which is designed as an extrusion part and has a greater wall thickness. The latter is expedient so as to be able to better machine this part.
The collecting tube and the collector are two separate structural components which can be connected to one another, preferably brazed to one another. For such brazing, it is expedient to fix both parts to one another before the whole condenser is placed in the brazing furnace for brazing. In the known condenser, this fixing is done by tack-welding. For a brazed condenser, such an operation is not typical, i.e. it is disadvantageous from the point of view of production technology, since it is expensive.